THE PRODUCTION OF PLASTIC LUBRICANTS BASED ON REGENERATED SYNTHETIC MOTOR OILS USED IN UZBEKISTAN

The purpose of the study is to increase the efficiency of using used engine oils as a dispersion medium for plastic lubricants. It has been established that the removal of resins, carbenes, carbides and asphaltenes from used synthetic motor oils makes it possible to obtain an oil base close to commercial base oils in terms of basic characteristics; refined oils also have a high margin of operational properties. The composition of lubricants for analogues of Lithol-24 and Solidol-Z based on refined used engine oils has been determined. Anticorrosive, adhesive and strength properties of lubricant compositions are considered.

Cement-free refractory concretes. Part 10. Rheological aspect of technology

The features of the rheological behavior of CFRC matrix systems are considered as highly concentrated dispersed systems. They are characterized by a dilatative, thixotropic and thixotropic-dilatant nature of the flow, depending on the composition, concentration, dispersion, and a number of other factors. The equation of the concentration dependence of the viscosity of suspensions (Pivinskii equation) is proposed. It is shown that the determining factor is the content of a kinetically free dispersion medium in them. The effect of the content of grain aggregate on the rheological properties of foundry systems is characterized. The significant effect of polydispersity of the particles of the solid phase and the temperature on the rheological properties of the HCBS with the dilatant nature of the flow is shown. The data on the effect of defloculation and stabilization of matrix systems on their rheological properties, which determine the reeterological properties of molding systems to obtain CFRC. Ill. 13. Ref. 50.

Gas-phase crosslinking of the lignin on the nanoscale fumed silica surface

A method for the polymerization modification of nanoscale fumed silica by crosslinking a lignin layer adsorbed on a nanosilica surface under a gas dispersion medium is described. A mixture of phenol and formaldehyde in the presence of HCl proved to be the most effective crosslinking agent. It has been suggested that the crosslinking of lignin molecules occurs by a mechanism similar to the production of phenol-formaldehyde resins.

Preparation and Evaluation of a Powdered Rebamipide Mouthwash as In-Hospital Formulation: Considering Dispersion before Use in Patients

In Japan, rebamipide (RB) mouthwash (RB-MW) for oral mucositis induced by cancer chemotherapy has been prepared using in-hospital formulation. Usually, RB-MW is prepared by dispersing crushed commercial RB tablets in the dispersion medium; however, uniformity is difficult to obtain due to low solubility. The current study aims is to prepare homogenously dispersed formulations using the fine particles of crushed tablets by a method that is convenient for hospital use. Commercial RB tablets were pre-milled at different milling times as “RB-Ts”. A ground mixture was then prepared by co-grinding the RB-Ts with HPC-L or PVP K30 via a benchtop ball milling machine (MM400). The physicochemical properties of samples were evaluated for PXRD, FTIR, turbidity, particle size, and solubility. Although the milling of RB tablets decreased the crystallinity, the length of milling time did not affect them. In contrast, grinding using MM400 significantly decreased RB crystallinity; their PXRD patterns showed a halo, suggesting the amorphization of RB crystals by grinding. Although solubility and turbidity seemed to be affected by the type of polymer rather than the particle size, every ground mixture showed high dispersibility. Thus, grinding the RB-Ts with polymers appeared to be the most promising way to obtain stable dispersion as an in-hospital formulation.

Experimental study of the stratification of polydisperse emulsions in a cell with heated walls

Experimental studies of the gravitational deposition of a polydisperse water-in-oil emulsion under heat influence are carried out. When the rate of thermal convection exceeds the rate of precipitation, partial delamination of the emulsion is found to occur. The viscosity of the dispersion medium decreases with increasing temperature, which contributes to an increase in the deposition rate of water droplets in the emulsion. In the presence of a temperature difference, convective flows occur in the liquid, while the drops of the emulsion coagulate and form larger agglomerates that settle faster to the bottom of the cell.

The Mechanisms of Antibacterial Activity of Magnesium Alloys with Extreme Wettability

In this study, we applied the method of nanosecond laser treatment for the fabrication of superhydrophobic and superhydrophilic magnesium-based surfaces with hierarchical roughness when the surface microrelief is evenly decorated by MgO nanoparticles. The comparative to the bare sample behavior of such surfaces with extreme wettability in contact with dispersions of bacteria cells Pseudomonas aeruginosa and Klebsiella pneumoniae in phosphate buffered saline (PBS) was studied. To characterize the bactericidal activity of magnesium samples with different wettability immersed into a bacterial dispersion, we determined the time variation of the planktonic bacterial titer in the dispersion. To explore the anti-bacterial mechanisms of the magnesium substrates, a set of experimental studies on the evolution of the magnesium ion concentration in liquid, pH of the dispersion medium, surface morphology, composition, and wettability was performed. The obtained data made it possible to reveal two mechanisms that, in combination, play a key role in the bacterial decontamination of the liquid. These are the alkalization of the dispersion medium and the collection of bacterial cells by microrods growing on the surface as a result of the interaction of magnesium with the components of the buffer solution.

Sonication effect on foam properties of egg white

The aim of this study was to determine the effect of ultrasound treatment on foaming properties of egg white. The samples were sonicated at 20/40 kHz and 180/300 W equipment power (3.7/6.9 W absorbed power) for 30, 45 and 60 minutes. Foam capacity had been increased by 25% due to sonication at 40 kHz and 6.9 W absorbed power for 60 minutes. This phenomenon may be caused by the homogenization effect of ultrasound and protein exposure of hydrophobic groups that improve the adsorption of protein onto the air/water interfacial molecules. It is found that frequency and duration of the treatment have no significant impact on the changes in foam capacity, only the absorbed power. On the other hand, foam stability had been decreased during the ultrasonic treatment. We can assume that sonication decreases the potential difference between the dispersed particles and the dispersion medium and this may be the cause of the collapse of the foam structure due to ultrasound treatment. In this case frequency, treatment time, and the absorbed power had a significant effect on the stability.